Ink-jet printer

Abstract

An ink-jet printer includes a sheet feed-in mechanism 60 for feeding a paper sheet, a rotary drum 10 having a peripheral surface 11 of a size larger than the paper sheet to be fed by the sheet feed-in mechanism 60 , for rotating at a constant speed, a sheet holding system 20 for holding the paper sheet on the peripheral surface of the rotary drum, a print head 200 for printing an image by repeatedly ejecting ink onto the paper sheet held on the peripheral surface of the rotary drum 10 while the rotary drum 10 performs a predetermined number of rotations, a sheet separator 140 for separating the paper sheet from the peripheral surface 11 of the rotary drum, a sheet feed-out mechanism 160 for feeding out the paper sheet separated by the sheet separator 140 , a control unit 111 for controlling the sheet feed-in mechanism 60 , the rotary drum 10 , the sheet holding system 20 , the print head 200 , the sheet separator 140 and the sheet feed-out mechanism 160 . In particular, the control unit 111 is constructed such that the sheet holding system 20 , the print head 200 and the sheet separator 140 are sequentially driven on the basis of the number of rotations of the rotary drum 10.

What is claimed is:  
     
       1. An ink-jet printer comprising: 
       a rotary drum which is rotatable at a constant speed, said rotary drum having a peripheral surface for winding up a print medium;  
       medium loading means disposed near said rotary drum for loading the print medium on the peripheral surface of said rotary drum;  
       an ink-jet print head disposed to face the peripheral surface of said rotary drum for printing an image by repeatedly ejecting ink onto the print medium on the peripheral surface of said rotary drum while the print medium is moved relative to said ink-jet print head by rotation of said rotary drum;  
       medium removing means disposed near said rotary drum for removing the print medium on which the image has been printed by said ink-jet print head; and  
       control means for sequentially driving said medium loading means, said ink-jet print head and said medium removing means during a predetermined number of rotations of said rotary drum in a manner such that an initial complete rotation is assigned to loading of the print medium by said medium loading means without printing, a last complete rotation is assigned to removing of the print medium by said medium removing means without printing, and a remainder of the rotations is assigned to printing of the image by said ink-jet print head wherein said initial complete rotation and said last complete rotation are always performed so as to reduce positional deviation or vibration of the print medium.  
     
     
       2. An ink-jet printer according to claim  1 , wherein said medium loading means comprises: 
       means for feeding the print medium to the rotary drum; and  
       means for causing the print medium fed by said medium feed-in mechanism to be held on the peripheral surface of said rotary drum.  
     
     
       3. An ink-jet printer according to claim  1 , wherein said medium removing means comprises: 
       means for separating the print medium from the peripheral surface of said rotary drum; and  
       means for feeding out the separated print medium.  
     
     
       4. An ink-jet printer according to claim  3 , wherein said means for separating the print medium from the peripheral surface of said rotary drum comprises a separating member which is disposed at a position at which a leading end of the print medium is positioned when said print head has completed printing of the image on the print medium. 
     
     
       5. An ink-jet printer according to claim  4 , wherein the means for separating the print medium from the peripheral surface of said rotary drum further comprises means for displacing said separating member along the peripheral surface of said rotary drum when the print medium has a length which is different than that of a preceding print medium. 
     
     
       6. An ink-jet printer according to claim  4 , wherein the means for separating the print medium from the peripheral surface of said rotary drum further comprises at least one additional separating member disposed along the peripheral surface of said rotary drum. 
     
     
       7. An ink-jet printer according to claim  1 , further comprising: 
       a housing which houses said medium loading means, said rotary drum, said print head, said medium removing means and said control means; and  
       a movable table which is movable into and out of said housing together with components of at least said rotary drum and said medium loading means in a state where the components are mounted on said movable table.  
     
     
       8. An ink-jet printer according to claim  1 , further comprising: 
       a housing which houses said medium loading means, said rotary drum, said print head, said medium removing means, and said control means;  
       means for opening the housing; and  
       means for preventing opening of the housing during rotation of said rotary drum.  
     
     
       9. An ink-jet printer according to claim  8 , wherein said control means includes: 
       means for issuing an opening instruction signal to initiate opening of the housing; and  
       means for outputting a stop signal to stop driving of said rotary drum upon issuance of the opening instruction signal, and for enabling opening of the housing after a preset period of time has elapsed from the output of the stop signal.  
     
     
       10. An ink-jet printer according to claim  9 , further comprising an openable and closable cover attached to the housing, and a detector for detecting opening of said cover and for causing the opening instruction signal to be issued responsive thereto.